Operating-system-level virtualization is a server-virtualization
method where the kernel of an operating system allows for multiple
isolated user-space instances, instead of just one. We call such
instances containers. As containers use the host’s kernel they are
limited to Linux guests.

What is a QEMU/KVM guest (or VM)?

A QEMU/KVM guest (or VM) is a guest system running virtualized under
Proxmox VE using QEMU and the Linux KVM kernel module.

What is QEMU?

QEMU is a generic and open source machine emulator and
virtualizer. QEMU uses the Linux KVM kernel module to achieve near
native performance by executing the guest code directly on the host
CPU.
It is not limited to Linux guests but allows arbitrary operating systems
to run.

How long will my Proxmox VE version be supported?

Proxmox VE versions are supported at least as long as the corresponding
Debian Version is
oldstable. Proxmox VE uses a
rolling release model and using the latest stable version is always
recommended.

Proxmox VE Version

Debian Version

First Release

Debian EOL

Proxmox EOL

Proxmox VE 6.x

Debian 10 (Buster)

2019-07

tba

tba

Proxmox VE 5.x

Debian 9 (Stretch)

2017-07

2020-07

2020-07

Proxmox VE 4.x

Debian 8 (Jessie)

2015-10

2018-06

2018-06

Proxmox VE 3.x

Debian 7 (Wheezy)

2013-05

2016-04

2017-02

Proxmox VE 2.x

Debian 6 (Squeeze)

2012-04

2014-05

2014-05

Proxmox VE 1.x

Debian 5 (Lenny)

2008-10

2012-03

2013-01

How can I upgrade Proxmox VE to the next release?

Minor version upgrades, for example upgrading from Proxmox VE in version 5.1
to 5.2, can be done just like any normal update, either through the Web
GUI Node → Updates panel or through the CLI with:

apt update
apt full-upgrade

Always ensure you correctly setup the
package repositories and only
continue with the actual upgrade if apt update did not hit any error.

Major version upgrades, for example going from Proxmox VE 4.4 to 5.0, are
also supported. They must be carefully planned and tested and should
never be started without having a current backup ready.
Although the specific upgrade steps depend on your respective setup, we
provide general instructions and advice of how a upgrade should be
performed:

LXC is a userspace interface for the Linux kernel containment
features. Through a powerful API and simple tools, it lets Linux users
easily create and manage system containers. LXC, as well as the former
OpenVZ, aims at system virtualization, i.e. allows you to run a
complete OS inside a container, where you log in as ssh, add users,
run apache, etc…

LXD is building on top of LXC to provide a new, better user
experience. Under the hood, LXD uses LXC through liblxc and its Go
binding to create and manage the containers. It’s basically an
alternative to LXC’s tools and distribution template system with the
added features that come from being controllable over the network.

Proxmox Containers also aims at system virtualization, and thus uses
LXC as the basis of its own container offer. The Proxmox Container
Toolkit is called pct, and is tightly coupled with Proxmox VE. That means
that it is aware of the cluster setup, and it can use the same network
and storage resources as fully virtualized VMs. You can even use the
Proxmox VE firewall, create and restore backups, or manage containers using
the HA framework. Everything can be controlled over the network using
the Proxmox VE API.

Docker aims at running a single application running in a contained
environment. Hence you’re managing a docker instance from the host with the
docker toolkit. It is not recommended to run docker directly on your
Proxmox VE host.

You can however perfectly install and use docker inside a Proxmox Qemu
VM, and thus getting the benefit of software containerization with the very
strong isolation that VMs provide.